To format a partition, right-click on the partition (smaller rectangle) inside a disk and select Format partition.
Specify Volume Name and File System for the resulting partition, then press Format.
To confirm your decision, press Yes.
You can now preview your changes.
Press Apply operations, then – Apply.
Hard Disk Manager for Mac, HowTos: Mac OS X, Products for Mac OS X
Tags: format, HDM for Mac, mac, partition